2HP VCO (2010s–present)

Name: 2HP VCO
Brand: 2HP

It shouldn't sound this big in two horizontal inches, but plug it in, twist the tiny knob, and there's the CEM3340.

Overview

The 2HP VCO is just two horizontal Eurorack units wide, barely wider than a patch cable, with skiff-friendly depth. You'd expect it to squeak or wheeze. It doesn't. It puts out a full-bodied, harmonically rich analog tone. This is a real CEM3340-based analog oscillator, not a digital approximation or a minimalist waveform generator. The sound is thick, warm and musical, with a character that harks back to the Prophet-5 and Oberheim OB-X, and a clarity that cuts through dense patches. People reach for it because it sounds good, not because they're out of space.

It's the spiritual successor to 2HP's earlier OSC module. The VCO has tighter tracking, better stability and a stronger feature set. The OSC was charming but occasionally temperamental. The VCO tracks 1V/oct across 10+ octaves, which makes it usable for melodic leads, basslines and FM experiments. It isn't a feature monster. There's no wavetable scanning, no digital effects, no microtonal tuning. It generates triangle, sawtooth and square waves, all available at once, all analog. The square wave has a crisp, slightly hollow edge that suits pulse-width modulation. The sawtooth has a rounded aggression and never turns harsh. The triangle is smooth and fundamental-rich, and works for sub-bass or LFO duty at low frequencies.

It does go down to LFO rates, slowly and smoothly, without stepping or jitter. That's hard in a module this compact, where power regulation and thermal stability can make or break low-frequency performance. So it works as a lead oscillator or as a modulation source. Pair it with another VCO for FM, sync it to a digital oscillator for metallic clangs, or use it as a drone generator.

Specifications

Manufacturer	2HP
Production Years	2010s–present
Original Price	$134
Width	2HP
Depth	42mm
Power	+12V: 27mA, -12V: 24mA, 5V: 0mA
Oscillator Type	Analog VCO
Core Chip	Curtis CEM3340 (reissue)
Waveforms	Triangle, Sawtooth, Square
Outputs	Simultaneous triangle, sawtooth, square
FM Input	Linear FM
Sync Input	Hard Sync
PWM Input	Pulse-width Modulation control
Tracking	10+ octaves, 1V/Oct accurate
Color Options	Silver, Black

Key Features

The CEM3340 Resurrection

The heart of the 2HP VCO is the reissued Curtis CEM3340 chip, which analog synth purists revere for its rich, stable, harmonically complex output. The chip was originally found in the Sequential Circuits Prophet-5 Rev 2 and the Oberheim Matrix series. It fell out of production for decades and became a sought-after relic. When it was reissued, builders like 2HP brought it into the Eurorack format. The tone is vintage and immediate, warm without being muddy, bright without being brittle. Even a raw triangle wave has presence, depth and a slight organic wobble. Many modern designs either can't replicate that analog character or choose not to pursue it.

Minimal Footprint, Maximum Function

At 2HP wide, the module is a footprint experiment made real. Most oscillators in this category give up features or sound quality to save space. The VCO doesn't. It delivers three clean, simultaneous waveforms, linear FM, hard sync and PWM, without skimping on tracking or stability. The front panel is stripped down: a single tiny knob for coarse tuning, a minuscule push-button for fine-tuning (adjusted via a small screwdriver), and jacks for CV, FM, sync and outputs. There's no display and no menu diving. Voltage goes in, sound comes out. That pushes you to think about patching and modulation sources. And because it's so small, you can afford more than one. Stack three for a compact unison lead, or dedicate one solely to FM modulation.

Trim Pots and Hidden Depth

Under the surface, the VCO is more tweakable than its size suggests. The circuit board holds multiple trim pots, adjustable with a small screwdriver, for pitch tracking, triangle wave symmetry and sine wave shaping. There's no dedicated sine output, but the triangle can be adjusted to approximate a sine. These are user-accessible, not just factory-set. Documentation from 2HP confirms that one trim pot handles 1V/oct calibration, while others adjust waveform symmetry and roundness. You can dial the module in for tracking across your system, or voice it to taste.

Historical Context

The 2HP VCO emerged during the mid-2010s Eurorack boom, when skiff-builders and minimalists were pushing back against ever-larger, feature-packed modules. Companies like MakeNoise and Mutable Instruments were exploring complex digital-analog hybrids. 2HP asked how small a real analog oscillator could be. The answer was two HP. Eurorack prices were climbing and cases were filling up, and the VCO added genuine analog oscillation without eating real estate. It stood apart from the bloated do-it-all modules and from the wavefolding digital oscillators that dominated the budget end. It leaned on the proven CEM3340 for a sound that felt both classic and fresh. Competitors like the Intellijel Dixie or the Noise Engineering Loquelic Iteritas offered more features, but none matched the VCO's space-to-sound ratio.

Collectibility & Value

Today, the 2HP VCO typically sells for $120 to $160 on the used market, depending on condition and color. Silver and black versions are equally common, with no significant price difference. Unlike some boutique modules, it hasn't inflated in value, thanks in part to ongoing production and 2HP's commitment to fair pricing. It doesn't depreciate into obscurity either. Its reputation for reliability and tone keeps demand steady, especially among skiff users and minimalist builders. Units in working order with stable tracking are the norm, but there are a few failure points. The most commonly reported issue, though rare, is drift in 1V/oct tracking over time, often tied to aging components or inadequate warm-up. Some users have reported needing to recalibrate trim pots after extended use, particularly in systems with unstable power supplies. The tiny front-panel knob and push-button tuning system can also be fragile. Excessive force may damage the potentiometer or underlying PCB traces. When buying used, test tracking across multiple octaves, check waveform symmetry, and make sure the FM and sync inputs respond cleanly. Recapping isn't a common requirement yet, but service technicians note that early units may benefit from it if drift becomes persistent. Overall, the VCO is considered low-maintenance, more set and forget than constant tweaking.